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This study focuses on optimizing the performance of an uplink pairwise Non-Orthogonal Multiple Access (NOMA) scenario with and without the support of a relayer, while subject to jamming attacks. We consider two different relaying protocols, one where the sources and the destination are within range of each other and one where they are not. The relay node can be mobile, e.g., a mobile base station, an unmanned aerial vehicle (UAV) or a stationary node that is chosen as a result of a relay selection procedure. We also benchmark with a NOMA retransmission protocol and an Orthogonal Multiple Access (OMA) scheme without a relayer. We analyze, adjust and compare the four protocols for different settings using outage analysis, which is an efficient tool for establishing communication reliability for both individual nodes and the overall wireless network. Closed-form expressions of outage probabilities can be adopted by deep reinforcement learning (RL) algorithms to optimize wireless networks online. Accordingly, we first derive closed-form expressions for the individual outage probability (IOP) of each source node link and the relayer link using both pairwise NOMA and OMA. Next, we analyze the IOP for one packet (IOPP) for each source node considering all possible links between the source node to the destination, taking both phases into account for the considered protocols when operating in Nakagami-m fading channels. The overall outage probability for all packets (OOPP) is defined as the maximum IOPP obtained among the source nodes. This metric is useful to optimize the whole wireless network, e.g., to ensure fairness among the source nodes. Then, we propose a method using deep RL where the OOPP is used as a reward function in order to adapt to the dynamic environment associated with jamming attacks. Finally, we discuss valuable guidelines for enhancing the communication reliability of the legitimate system.

Vietnam is among the top countries in the world at risk of natural hazards so that efficient real-time environment monitoring is becoming essential. The continuous development in information and communication technology is inspiring the development of the smart monitoring systems for environmental management and protection. This paper presents an energy efficient, long range sensor system for Internet of Things (IoT)-based smart environment monitoring and early warning. The proposed system combines the novel energy efficient temperature. Beat sensors integrated with the LoRaWAN communication protocol and web interface. The experimental results are achieved to clarify the efficiency of the proposed sensor system and its potential applications in the real systems.

This study explores an incremental relaying strategy in downlink pairwise Non-Orthogonal Multiple Access (NOMA), which involves multiple pairs of nodes near and far from the downlink destinations. The strategy aims to select a near destination node to relay the packet of a far destination node, considering the presence of jamming attacks. To this end, we first derive closed-form expressions for the individual outage probability (IOP) for both near and far destinations in Nakagami-m fading channels. Next, the overall IOP (OIOP) performance is defined as the maximum value among the obtained IOPs, ensuring fairness among the nodes. To optimize the system, simulated annealing algorithms are proposed to determine the best power allocation and the best relay-destination pairing. We can conclude that both the power allocation and the position/selection of the near destination node significantly impact the OIOP for a specific pair. However, in the case of multiple pairs of destinations, a good power allocation alone suffices for each pair, and fixed or even random destination pairing is satisfactory in the considered context.

Proper relay selection (RS) plays a key role for improving the reliability of wireless networks, especially in the presence of jamming attacks and/or interferers. In this work, we consider several RS schemes from the literature, using e.g. channel gains and signal-to-interference plus noise ratio (SINR) to select a relayer and evaluate them using outage probability (OP). We also propose an RS scheme which is selecting relayers to maximize the communication reliability in terms of minimizing the OP. The suggested RS strategy also takes the effect of jamming attacks and/or interferers into account. Accordingly, an intensive investigation of the OP of all RS schemes considering also jammers' positions in various scenarios is conducted. The results suggest that a combination of RS schemes using channel gains and SINRs of all hops achieves the best communication reliability in scenarios with intensive interference. The sensitivity for channel estimation errors of the relaying schemes is also investigated. Finally, discussions about the obtained results together with the complexity of all RS schemes are presented before providing guidelines on which schemes should be used in which scenarios to improve the communication reliability.

The edge computing paradigm brings the capabilities of the cloud such as on-demand resource availability to the edge for applications with low-latency and real-time requirements. While cloud-native load balancing and scheduling algorithms strive to improve performance metrics like mean response times, real-time systems, that govern physical systems, must satisfy deadline requirements. This paper explores the potential of an edge computing architecture that utilizes the on-demand availability of computational resources to satisfy firm real-time requirements for applications with stochastic execution and inter-arrival times. As it might be difficult to know precise execution times of individual jobs prior to completion, we consider an admission policy that relies on single-bit execution time predictions for dispatching. We evaluate its performance in terms of the number of jobs that complete by their deadlines via simulations. The results indicate that the prediction-based admission policy can achieve reasonable performance for the considered settings.

Some types of Cyber-Physical System (CPS) applications found within e.g., quarrying, mining, harbors, and construction sites, operate within confined areas. To guarantee that communications between nodes in such systems operate smoothly, the adopted wireless communication protocols must meet stringent requirements, even in the presence of interference and/or jamming. This thesis work targets finding performance metrics suitable for designing and evaluating wireless networks when used for CPSs in confined areas. Given the shortage of spectrum and the increased risk of cyber-attacks experienced lately, the protocols must also be adjusted to perform well when subject to strong interference and/or adversary jamming. Hence, to be useful in practice, metrics that can be recalculated during runtime are needed, such that they can be used not only to propose, select and tailor the communication protocols to fulfill the stringent CPS requirements but also to optimize their performance during runtime. The literature survey conducted in this thesis shows that a reliability metric in terms of thresholding the so-called outage probability is valuable for all design steps as well as for continuously optimizing the communications. However, since the outage probability is defined as the probability that an individual wireless link will experience outage, it does not address the reliability of the entire network within the confined area. The thesis work shows that it is possible to consider overall outage probabilities and evaluates the probability of outage for each individual packet from a specific source node to a final destination, including all possible links in the network. This way, it is possible to consider the overall outage for all packets within the network in the confined area. Outage probability measures are defined for different system models and closed-form expressions for the outage are derived for the Individual Outage Probability (IOP), the Overall Outage Probability (OOP), the IOP for one packet (IOPP), and the OOP for all packets (OOPP), with and without the presence of attackers and/or strong interference. These reliability metrics can be adopted to analyze the effects of a wide range of parameters such as power allocation, node positions, the use of relay nodes or retransmissions, etc. on the individual link, individual source packet, and overall network reliability. The analysis thereby makes it possible to provide a set of general guidelines for tailoring the protocols and enhance the communication reliability of all legitimate nodes in the CPS. Having the closed-form expressions readily available also enables recalculating and adjusting parameters faster in order to find the best solution to improve the communication reliability during runtime. The thesis work demonstrates how outage probability can be used to enhance system performance in several example scenarios, including a multiple access scheme, pairwise Non-Orthogonal Multiple Access (NOMA), mobile access points and/or relay nodes. The outage analysis can thereby be applied to an existing CPS application to enhance reliability, robustness, and flexibility while maintaining a low delay.

Vissa typer av trådlösa närverk kopplar samman maskiner och människor som samarbetar inom ett begränsat område, exempelvis ett stenbrott, en gruva, en hamn eller en byggarbetsplats. För att garantera att kommunikationen mellan olika noder i sådana system fungerar smidigt, måste de trådlösa kommunikationsprotokollen leva upp till stränga krav, även då olika typer av störningar inträffar. Arbetet i den här doktorsavhandlingen syftar till att hitta prestandamått som är lämpliga både för att designa och för att utvärdera trådlösa nätverk som används för att koppla samman olika aktörer som samarbetar inom avgränsade områden. Med tanke på bristen på spektrum och den ökade risken för cyberattacker som uppmärksammats den senaste tiden, behöver kommunikationsprotokollen också anpassas för att prestera bra när de utsätts för kraftiga störningar och/eller cyberattacker. För att vara användbara i praktiken krävs mått som kan utvärderas under körning, så att de inte bara kan användas för att utveckla, välja eller skräddarsy kommunikationsprotokollen, utan också för att optimera deras prestanda direkt under körning.Litteraturundersökningen som genomförts i denna avhandling visar att ett tillförlitlighetsmått som använder tröskelvärden för den så kallade” outage probability” (sannolikheten för avbrott i den trådlösa kommunikationen) är värdefullt för att utveckla såväl som för att kontinuerligt optimera kommunikationsprotokoll. Problemet är att sannolikheten för avbrott definieras som sannolikheten att en enskild trådlös länk kommer att drabbas av ett avbrott. Det inbegriper alltså inte tillförlitligheten för hela nätverket inom det begränsade området. Avhandlingen visar att det är möjligt att formulera övergripande prestandamått som kan användas för att utvärdera sannolikheten för avbrott för varje enskilt paket från en specifik källa till en specifik slutdestination även då paketet tillåts använda alla tillgängliga länkar i nätverket. På så sätt är det möjligt att utvärdera den totala sannolikheten för avbrott i kommunikationen för alla paket som ska kommuniceras inom hela nätverket. Sannolikhetsmåttet för avbrott i kommunikationen kan därmed definieras för olika systemmodeller och uttryckas i sluten form för avbrott på en specifik länk, ett specifikt paket, alla länkar eller alla paket i nätverket, och detta både med och utan närvaron av en angripare och/eller starka störningar. Dessa tillförlitlighetsmått kan således användas för att analysera effekterna av flera viktiga parametrar såsom fördelning av signalstyrka mellan noderna, nodernas relativa positioner, användningen av särskilda relänoder eller av omsändningar. Analysen gör det därigenom möjligt att tillhandahålla en uppsättning allmänna riktlinjer för att skräddarsy kommunikationsprotokollen och förbättra kommunikationssäkerheten för alla legitima noder i nätverket. Att ha väldefinierade matematiska uttryck för tillförlitlighetsmåtten möjliggör också omräkning och justering av parametrar snabbare och därmed hitta den bästa lösningen för att förbättra kommunikationens tillförlitlighet direkt under körning. Avhandlingsarbetet visar hur sannolikheten för avbrott kan användas för att förbättra systemets prestanda i flera exempelscenarier, inklusive system som tillåter att flera användare kommunicerar samtidigt, eller de som har mobila accesspunkter och/eller relänoder. Att analysera sannolikheten för avbrott i kommunikationen kan därmed appliceras på ett befintligt kommunikationssystem för att förbättra tillförlitligheten, robustheten och flexibiliteten samtidigt som en låg fördröjning kan bibehållas.

The use of wireless devices in industrial sectors has increased due to its various advantages related to cost and flexibility. However, legitimate wireless communication systems are vulnerable to cybersecurity attacks, due to its inherent open nature. Detection of rogue devices therefore plays a crucial role in critical wireless applications. In this paper we design a deep convolutional neural network (DCNN) to classify legitimate and rogue devices using raw IQ samples as input data. An algorithm is presented to find the optimal number of convolutional layers and number of filters for each layer under an accuracy constraint, in order to enable fast prediction time. Furthermore, we investigate how wireless channel models affect the accuracy and prediction time of the designed DCNN model. Our obtained results are benchmarked against previous DCNN models. Moreover, we discuss how the systems should react to a detected rogue device, considering the IEC 62443 standard.

Fingerprinting positioning aided by wireless technologies plays an important role in a variety of industrial applications, such as factory automation, warehouse automation, and underground mining, where guaranteeing a position prediction error smaller than a threshold value is necessary to meet certain functional requirements. In this paper, we firstly design a deep convolutional neural network that uses the channel impulse response measurement as an input parameter to predict the position of a mobile robot. Second, we propose a simulated annealing algorithm that finds a minimum number of access points with their respective optimal positions that satisfies an expected average distance error in terms of a mobile robot's predicted position. The obtained results show that the average distance error is significantly reduced, e.g., by half compared to the case without optimal positions of access points.

In this paper, an uplink pairwise Non-Orthogonal Multiple Access (NOMA) scenario using a mobile access point (AP) or an unmanned aerial vehicle in the presence of a jamming attack is considered. To mitigate the influence of the jamming attack, a joint power allocation and AP placement design is proposed. Accordingly, closed-form expressions of the overall outage probability (OOP) and the individual outage probability (TOP) considering imperfect channel state information for each of the source nodes the AP serves, are derived over Nakagami-m fading channels using dynamic decoding order and fixed pairwise power allocation. We conduct an investigation of the effect of different parameters such as power allocation, source node placements, AP placement, target rates, and jammer location on the OOP and the IOP performance. By adapting the power allocation and the AP placement to the jamming attack, the communication reliability can be increased significantly compared to neglecting the presence of the jammer or treating the jammer as noise. Since the malicious jammer and the AP have conflicting interests in terms of communication reliability, we formulate a non-cooperative game for the two players considering their positions and the power allocation of the NOMA nodes as their strategies and the OOP as utility function. We propose using hybrid simulated annealing - greedy algorithms to address the joint power allocation and AP placement problem for the cases of both a fixed and a mobile jammer. Finally, the Nash equilibrium points are obtained and then the UAV goes directly to this position and keeps staying there to save power consumption.

Within the context of Industry 4.0, many devices have become more intelligent and connected, leading to challenges on how to meet the stringent requirements on latency and reliability in networks of critical cyber-physical systems. In particular, timely channel access and high reliability are of essence to guarantee real-time deadlines. To this end, time-division multiple-access (TDMA) schemes are often used in industrial applications to get contention-free access to the channel. Using pairwise non-orthogonal multiple access (NOMA) on top of such an existing TDMA scheme has recently emerged as a promising solution. With pairwise NOMA, two nodes are served simultaneously using the same time-frequency resources but with different power levels. To separate the signals, successive interference cancellation is used at the receiver. In addition, by adjusting the power allocation, pairwise NOMA can easily switch to TDMA by assigning zero power to one user, if and when needed. Due to this flexibility, pairwise NOMA can be integrated into existing wireless networks and schedulers with improved performance as a result. In particular, if pairwise NOMA could be tailored to the requirements of systems of collaborating cyber-physical systems, it would be possible to enhance performance in terms of latency and reliability, while still providing timely channel access to critical users using TDMA. This is the scope of the thesis work.

In order to evaluate the communication reliability for each user in the system as well as for the overall system, the individual outage probability (IOP) and the overall outage probability (OOP) are of essence, but have so far not been available for pairwise NOMA used on top of TDMA. In this thesis work, closed-form expressions for the IOP and the OOP of both uplink and downlink NOMA are derived – also in the presence of a mobile smart jammer. Using these performance metrics, insightful guidelines on the impact of some key parameters on the communication reliability such as power allocation, decoding order, node placements and so on are provided. It should be noted that the conclusions on node placement can be used for smart user pairing, but also for placement of access points (AP) or even mobile APs, using a UAV. Moreover, by formulating a non-cooperative game between a malicious smart mobile jammer and a friendly mobile AP serving two friendly sensor nodes simultaneously, Nash equilibrium points are obtained to reduce power consumption for the AP, while satisfying the communication reliability requirements. Using the derived expressions for OOP and IOP to select proper settings for pairwise NOMA, it is shown that NOMA can be tailored to ensure user fairness, provide timely channel access and high reliability, which is useful for enhancing performance of critical cyber-physical systems even in the presence of jamming.